Switch for electric circuits.



G. WRIGHT.

SWITCH POR ELECTRIC GIRGUITS.- APPLIOATION FILED Nov. s, 1904.

996,387, Patented June 27, 1911.

Inventor: Gilbejt Wright.

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GILBERT WRIGHT, OF PITTSEIELD, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SWITCH FOR ELECTRIC CIRCUITS.

Application led November 8, 1904.

To all whom it may concern:

Be it known that I, GILBERT WRIGHT, a citizen of the United St-ates, residing at Pittseld, county of Berkshire, State of Massachusetts, have invented cert-ain new and useful Improvements in Switches for Electric Circuits, of which the following is a specification.

My invention relates to switches for electric circuits, and has particular reference to switches of the type in which contacts are immersed in oil.

It is common practice in controlling` circuits carrying currents of large amount, or at high voltages, to employ switches arranged to break the circuit in oil, since the arcing is thereby greatly reduced. In switches for circuits of high current capacity it is important that good contact should be maintained at all times between the stationary and movable contacts. To this end it is essential that the contacting surfaces of both stationary and movable contacts should remain perfectly smooth, and should not be injured by the arcing which is formed in opening the switch. It is also essential, in case of faulty adjustment or accidental displacement of one or more of the contacts` that the contacts should be completely selfalining so as to maintain the entire contact surfaces in engagement.

One feature of my invention consists in a novel form of contact adapted to meet the above requirements. This contact is so arranged that the surface from which the arc springs is not the elfective contacting surface when the switch is closed and the contact is made completely self-alining in all directions.

A second feature of my invention consists in a novel arrangement of the stationary contacts and their insulators. It is customary in oil switches to extend the stationary contacts through the cover of the oil-containing vessel and to surround these conductors with tubular insulators supported by the cover and supporting the contacts. To Secure a firm engagement between the insulators and the contacts, it has been customary to cement the contacts within the insulators. This construction is objectionable, since bursting strains may be produced by expansion of the contact, which result in cracking the insulator. By my invention the internal diameter of the insulator is made Specication of Letters Patent.

Patented June 27, 1911. sei-m1 No. 231,840.

considerably larger than the diameter of the contact extending through it, and the contact is supported at the ends of the insulator in such manner that compression strains are produced on the insulator, rather than strains tending to burst it.

My invention will best be understood by reference to the accompanying drawings, in which- Figure l shows a side elevation of a switch arranged in accordance with my invention; Fig. 2 is a cross-sectional view, parts of the switch being shown in elevation, Fig. 3 shows an enlarged det-ail of a movable contact; and Fig. t shows a side view of the same.

In the drawings I have shown my invention applied to the type of switch disclosed in Patent No. 761,745, issued to me J une 7, 1904; but it will be understood, however, that my invent-ion is not limited to this particular type of switch.

In the drawings A represents a tank adapted to contain oil, which is supported from the frame or cover B. Mounted within this frame or cover are the tubular insulators C, through which eXtend the stationary contacts D. rlhe construction of insulators and contacts is clearly shown in Fig. 2. It will be seen that the contact D is in the form of a bolt with a flat head rounded at the edges and adapted to engage the lower end of the tubular insulator C. E represents a cap mounted on the upper end of the contact D and forced into engagement with the upper end of insulator C by means of the nut d. e e represent flexible washers of asbestos or other suitable material inserted between the ends of the insulator and the head of contact D and the cap E, respectively. It will be seen that this construction forms a rigid connection between the contact and the supporting insulator, but that space is left for the eXpansion of the contact and that all strains upon the insulator are compression strains instead of strains tending to burst the insulator. It is evident that when the nut d is loosened the bolt-shaped contact D may be rotated in the tubular insulator. The contact D is provided at the upper end with another nut Z by means of which the switch leads may be secured to the contact terminal.

The moving parts of the switch are all supported from the longitudinal reciprocating rod F, which is supported in suitable guides f f on the cover B. Any suitable means for moving the rod F may be employed. I have shown the rod provided on its front end with a rack adapted to be engaged by the gear G (indicated in dotted lines), to the shaft of which is secured the operating handle H. Supported from the reciprocating rod F by means of the bolts I I are two insulating bars J J placed one above another, as shown. One of these bars is slotted to receive a member K of channel sect-ion, which extends transversely between the two bars J J and is held rigidly clamped between them by means of the clamping bolts L L.

At each end of each member K is carried a mo fable contact M, the construction and arrangement of which is clearly shown in Figs. 3 and 4t. The head of this contact is shaped exactly like the head of the stationary contact D. It is provided with a ball-shaped protuberance m which fits within a tubular socket formed in the member K. This ball and socket connection between the contact M and the member K leaves the contact free to aline itself in any direction whatever with the stationary contact D, and also permits the contact to move axially in the socket. As a result of the ball-andsocket connection between the contact M and the supporting member, the contact may be rotated, if desired. It is advantageous to rotate both the contact D and the contact M at intervals, so as to provide new breakpoints between the contacts whenever the contacts become pitted or burned at the old break-points. rIhc contacts may be rotated by hand whenever desirable. The contact M is pushed upwardly into engagement with the stationary contact by a leaf spring N. The cont-acts on opposite ends of each member K are connected by the flexible conductors O clamped between the nuts 0. The position of the upper nut 0 limits the forward movement of the contact M when it is disengaged from the stationary contact by the opening of the switch.

The operation of the switch will be evident from the foregoing description. In Fig. l the switch is shown in its open position. As the switch is moved in either direction to one of its closed positions, the curved edge of a movable contact engages the curved edge of a stationary contact and the movable contact is forced downward against the leaf spring N, so as to slide under the stationary contact. A wiping engagement between the stationary and movable contacts is thus obtained, which serves to keep the contact surface clean and smooth. The ball and socket support of the movable contact permits it to aline itself completely with its stationary contact wholly independently of its support and of the other contact carried by the support. liVhen the switch is again opened, the movable contact rubs over the surface of the stationary contact until their edges come together. At this point the movable contact is pushed upward by the leaf spring N so that its rounded edge is rubbed over the rounded edge of the stationary contact. Thus, the arc which is finally produced upon their separation occurs between t-hc rounded edges and not between the flat bearing surfaces.

As stated heretofore, my invention is not limited to the particular type of switch in connection with which I have chosen to illustrate my invention. Consequently, I do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the appended claims to cover all modifications which are within the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. In a switch for electric circuits, a contacthaving a fiat bearing surface, a cylindrical socket, and a ball-shaped protuberance carried by said contact and fitted within said socket to slide longitudinally of said socket and to permit said contact to rock about said protuberance.

2. In a switch for electric circuits, a spring-actuated contact, a tubular socket, and a ball-shaped protuberance carried by said contact and fittting within said socket.

3. In a switch for electric circuits, a flathe'aded contact provided with a shank at right angles to the'contact surface, a tubular socket surrounding said shank, a ball-shaped protuberance on said shank fitting said socket, a spring pressing said contact outwardly from said socket, and means for limiting the movement of said contact.

t. In a switch for electric circuits, a reciprocating member provided with a plurality of tubular sockets, a plurality of contacts each having a shank with a ball-shaped protuberance fitting within one. of said sockets, springs operatively connected to said contacts, and flexible conductors connecting said contacts.

5. In a switch for electric circuits, a contact having a flat head with rounded edge, a shank extending at right angles to said head, a ball-shaped protuberance on said shank, a supporting member having a tubular socket adapted to receive said protuberance, a spring pressing said shank outwardly from said socket, and means for limiting the movement of said shank.

6. An electric switch comprising coperating contacts which have flat engaging surfaces and one of which has a shank with a rounded protuberance, a movable operating member provided with a tubular socket for receiving said spherical protuberance and mounted to bring the flat surfaces of said contacts into sliding engagement, and a spring mounted in said member to engage said shank.

7. An electric switch comprising relatively movable coperating contacts which have flat engaging surfaces and one of which has a shank With a rounded protuberance, an operating member mounted to reciprocate in a direction parallel to said contact surfaces and having a tubular socket to receive said spherical protuberance, a spring on said member for engaging the shank of said contact, a flexible conductor connected to said contact, and means for reciprocating said operating member.

8. An electric switch comprising a stationary Contact having a iiat engaging surface, an operating member mounted to reciprocate in a direction parallel to said surface and provided With a tubular socket in alinement With said fixed contact, a movable contact having a shank With a rounded protuberance mounted in said socket, a spring carried by said member for engaging said movable contact to press it into engagement with said fixed contact, and a flexible current carrying conductor connected to said movable contact.

9. An electric switch comprising a contact having a flat engaging surface and a shank perpendicular to said surface, a support for said contact having an opening in which said shank fits loosely, clamping means c0- operating With said shank to normally hold said contact stationary, a coperating movable contact having a flat engaging surface and a shank With a rounded protuberance, a flexible current carrying conductor connected to said movable contact and an operating member provided With a tubular socket for receiving said spherical protuberance, said member being movably mounted to bring the engaging surface of said contacts into sliding engagement.

In Witness whereof I have hereunto set my hand this fifth day of November, 1904.

GILBERT WRIGHT.

Witnesses:

SAMUEL E. WIDDIFIELD, HELEN SMITH.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

